function ver_value = compute_vertice(node)
b1 = @(x,y) 1 - 2.*x;
b2 = @(x,y) 2.*x + 2.*y -1;
b3 = @(x,y) 1 - 2.*y;
ver_value = zeros(3,1);
ver_value(1) = b1(node(1),node(2));
ver_value(2) = b2(node(1),node(2));
ver_value(3) = b3(node(1),node(2));
end